Metallic stair construction.



W. DOWLING & W. A. SCHROEDER.

METALLIC STAIR CONSTRUCTION.

APPLICATION FILED MAY 25, 191A.

1,138,642. I Paten' May 11, 1915.

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METALLIC sirius, consfrneerrcn.

, specification.

Uur invention relates to metallic stair construction, and has for its principalobject the provision of n. very firm, close and rigid connection between the treads and risers and stringers of the stairs'.

A further object' is to greatly reduce the cost of metallic stair construction.

of a portion of a Stringer and a tread illusu vtrating a feature of our invention. Fig. E3

is a vertical section through a trend, showu ing portions of the risers and 'e Stringer. Fig. 3 is a detail illustrating a joint hetWeen a'stringer and e tread. Fig. 4 shows a modified form of treed. Fig. 5 is a sectionof the same illustrating the joint between the tread and Stringer. Fig. 6 is a modification illustrating the finish of a joint for u plain metallic treed. l

By referenceto the accompanying drawing, it will be'understood that 1 represents a Stringer of. the stair construction, and 2 the tread. As illustrated in Fig. 2, it may he den sireble to hare the risers 4 formed integraly with the subjacent tread and secured to the ment for dirt, and a place of ingress for.

the tread and riser and the Stringer, with the result that the stairs are inclinedto he Webbly, and the space left provides legdwater, which renders the stairs leaky and the' members subject toA rusting out. i

l'n our improved construction, the stringers 1 are pierced with apertures, preferably Specication of Letters Eetent. Application mea my 25, im. serial no. starre.

the connection 'between ther :ententes may it'. reis.

twc, as illustrxitedin Fig. 2, just-below the level of each treed, which apertures are adapted for the'reception of en angle bolt 6.

The treads are ikewise ieroed with apen tures 7 which are adapte to receive the u turned end 6Es of the angle holt. In. t e angle,the holt is provided with e notch 6" of height suiieient to just-receivethe thickness of the tread, and of depth sueient te secure a bite or purchase thereon.

In assembling the stairs, the bolts s re placed in the apertures of the stringere end the nuts started thereon. The 'trends ere then laid 'on over the ends of the bolts, end' the nuts then screwed up tight, causing the bolts to engage the. treed in their notches, dand drew the tread and stringere closely together, forming en absolutely tight thaiti', joint, which for cli prscticei purpeses is .water proof when the perte are properly* shaped.. The heit provides a. support for the tread :and riser, and the notch holds the tread firmly down on the horizontal ertion of the boit-nud prevents its huclzi away under the compression resulting from the tightening of the nut. iin case the' stairs are to he inished with concrete or composition treads, as illustrated in Figs. l and 2, the plasticcomposition is then put in, cover ingr and encompassingthe upwardly 'extending ends ot the bolts. 'ii'hen the com osition sets, it is thu. interlocked with oth the stringers and thi tread by virtue of its engagement with the bolts.

While we have slown a structure employing but four bolts to each trend, two at erich ond, itfvis obvious that more bolts may be employed if desired.

ln Figs. 4 and 5, we have illustrated e modification in which channels Q are stamped in the tread, and the bolts leid im' the channels. This construction gives` e greater bearing area. between the ends of the trends end the stringere.

ln Fig. 6 is iilustrated the yholt may he finished by e nut S screwed. on tov the upwardly projecting end, which construction mev he. einnoyed in instances wherein e concrete treat is not used en top of the metallic tread.

This form of construction secures e very rigid stair structure, as the stringere, treads and risers may be drawn together and held a method in which being a sint mrmef in she upwm'ly Esami 

